1. Field of the Invention
The present invention relates to a photocatalyst compound and to a process for production thereof.
2. Description of the Prior Art
Photocatalysis is known and has application in treatment of fluids such as water containing pollutants.
Conventionally, a photocatalyst such as titanium dioxide (TiO.sub.2) is added to the fluid to be treated to form a slurry. The slurry is then exposed to electromagnetic radiation which would result in the catalytic destruction or decomposition of the pollutants in the fluid. For TiO.sub.2, radiation having a wavelength of less than or equal to about 380 nm results in catalytic destruction or decomposition of the pollutants in the fluid.
It is known in the art to load TiO.sub.2 on a support to facilitate recovery of the TiO.sub.2 in a specific place. However, as is known in the art, TiO.sub.2 is a relatively poor adsorber of, inter alia, organic compounds and there has been little or no attention given to this in the art.
Indeed, much of the prior art has focused on methods of immobilizing the photocatalyst TiO.sub.2 directly on to the support material. Generally, this technique involves thermal fusing of TiO.sub.2 to a support material such as silica gel, etched glass beads, interior of glass tubes, Teflon.TM. tubing, woven glass mesh, sand and the like. See, for example, any of the following prior art references:
1. Serpone et al., Solar Energy. Mater. 14, 121 (1986), PA0 2. Matthews et al., Anal. Chim. Acta. 223, 171 (1990), PA0 3. Matthews, Solar Energy Mater. 38, 405 (1987), PA0 4. U.S. Pat. No. 5,182,030 (Crittenden et al.), PA0 5. Australian patent application PH7074 (Mattews), PA0 6. Stakheev et al., J. Phys. Chem. 97, 5668 (1993), PA0 7. Matthews, Wat. Res. 25, 1169 (1991), PA0 8. Yoneyana et al., J. Phys. Chem. 93 4833 (1989), PA0 9. Yamanaka et al., Mater. Chem. Phys. 17, 87 (1987), PA0 10. Minero et al., Langmuir8, 481 (1992), and PA0 11. U.S. Pat. No. 4,495,041 (Goldstein),
the contents of each of which are hereby incorporated by reference.
While there appears to exist a commercial interest in TiO.sub.2 -based photocatalysis for the destruction or decomposition of pollutants in water, the known systems suffer from a number of disadvantages.
Specifically, a disadvantage of the work done to date is that, with most of the supported TiO.sub.2 photocatalysts, there is a drop-off in the photoactivity of the photocatalysts compared to the photoactivity of unsupported TiO.sub.2 photocatalyst.
Yet another disadvantage is that, with most of the prior art supported TiO.sub.2 photocatalysts, there is a drop-off in the adsorption of pollutants by the photocatalysts compared to the adsorption characteristics of the support material, per se, due to the unfavourable adsorption characteristics of TiO.sub.2.
It would be desirable to have a photocatalyst compound alleviate at least one of the above-identified disadvantages of the prior art.